Hello Kit, I dont have any other good advice here, but the one thing I can say is , I think it is a lot harder with a daughter/mother than with the mother/son. I myself know that my daughter is MUCH more vulnerable and able to be "hurt" in life than my son.
My prayers and support go to you as a fellow participant in this ongoing madness called addiction. I was a former addict when I was in my 20's before I married my husband, and that was also a contributing factor to my ongoing codie behavior and enabling of my son thinking he would "grow out of" the drug use like I did DOH!